MONDAY, Dec. 4 (HealthDay News) -- Heart patients with drug-eluting stents implanted to keep their arteries open were found to have a much higher risk of sudden death than those getting bare metal stents if they stopped taking the blood thinner Plavix, a new Swiss study reports.

The findings were released Monday in advance of a critical U.S. Food and Drug Administration advisory panel meeting later this week that will consider the safety of drug-eluting stents.

There has been growing concern about the long-term safety of drug-eluting stents. The Swiss study links the danger specifically to discontinuation of Plavix (clopidogrel), a drug commonly prescribed for patients who have stents inserted after undergoing the artery-opening procedure called angioplasty.

The study of 746 people who had 1,113 stents implanted did show that drug-eluting stents did a better job of keeping arteries open.

But the risk for patients with drug-eluting stents who stopped taking Plavix seven to 18 months after angioplasty was clear. The incidence of death or heart attack for those patients was 4.9 percent, compared to 1.39 percent for patients with bare metal stents. The reason was a higher incidence of thrombosis, which is sudden blockage of an artery by a blood clot.

The findings will be published in the Dec. 19 issue of the Journal of the American College of Cardiology.

The immediate issue arising from the findings concerns the use of Plavix, U.S. cardiologists said.

"This study definitely raises the question of whether these drug-eluting stents should be anti-coagulated for a long period of time," said Dr. John Kao, an assistant professor of medicine at the University of Illinois at Chicago. "What that time period is, is, at this moment, unclear."

Drug-eluting stents now dominate the market, accounting for 80 percent to 90 percent of implants. That situation should continue, said Dr. Robert O. Bonow, director of cardiology at Northwestern University and a spokesman for the American Heart Association, because "they are very effective at preventing restenosis [closure of the artery]."

But in doing so, the drug-eluting stents may also prevent the regrowth of the normal tissue that lines the artery, increasing the risk of thrombosis, Bonow said. Plavix can counter that risk, he said.

"Until we know more, any cardiologist would recommend continued use of clopidegrel," Bonow said. "The uncertainty is how long we keep people on Plavix, indefinitely or for the first two years."

There might be a subset of angioplasty patients for whom bare metal stents are preferable, Bonow said, such as "patients who have more simple plaques [deposits] in large blood vessels." But drug-eluting stents are preferable in most cases, he added.

Money might enter into the decision of which stent to use, Kao said. Plavix therapy costs at least $120 a month, he said, and, "at least in my practice, when I evaluate someone who needs intervention, if the patient is on a fixed income and cannot afford to take Plavix for six to 12 months, I put in a bare metal stent."

Kao's recommendation for Plavix use by people who get drug-eluting stents is "at least a year, indefinitely if they can afford it."

People faced with angioplasty should be aware of "the upside and downside of a drug-eluting stent," Bonow said. "With Plavix, it usually is a risk worth taking."

SOURCES: John Kao, M.D., assistant professor, medicine, University of Illinois, Chicago; Robert O. Bonow, M.D., director, cardiology, Northwestern University, Chicago; Dec. 19, 2006, Journal of the American College of Cardiology